A combination of morphological, biochemical and genetic techniques will be used to elucidate the mechanism of assembly of the bacterial spore coat layers. This structure is composed of keratin-like proteins arranged into at least three distinct morphological components. The morphogenetic reactions required for the assembly of these layers will be studied in various bacilli and in mutants defective in coat formation. Particular attention will be given to processing reactions involved especially the role of intracellular proteases and secondary modifications of structural proteins. Various mutants will be mapped and coat genes will be purified for in vitro studies of control processes. Related studies will include a more detailed analysis of the function of intracellular proteases beyond their role in coat processing and attempts to further define the regulatory signals required to initiate speculation. In both cases, some mutants have already been isolated and phenotypic studies initiated; further refinements of the screening procedures should help in isolating other classes of mutants. We shall also initiate studies of the synthesis of spore coat related polypeptides deposited as crystals or parasporal bodies by some bacilli. The function of these crystals (other than some being toxic for certain insect larvae) and the regulation of their syntesis are of interest.